Process of producing decolorizing carbon



40 a second Patented July 21, 1925.

PATENT OFFICE.

E'MIL RENE, OF STASSFURT, GERMANY.

PROCESS OF PRODUCING DEGOLORIZING CARBON.

II'o Drawing. 7

To all whom it may concern:

Be it known that I, EMIL Hnnn, citizen of the German Republic, residing at Sulzestrasse, Stassfurt, Germany, have invented I new and useful Improvements in a Process of Producing Decolorizing Carbon, of which the following is a s ecification.

This invention re ates to an improved process of producing the so called active or de- 1 colorizing carbon, its obj ect being to produce highly efficient decolorizing carbon havmg a strong decolorizing power on the. usual liquids to be decolorized by relatively simple and inexpensive operations and from cheap (11611138. lggarding the present state of the decolorizing carbon producing art of which I am aware, I know, that it has already been roposed to produce decolorizing carbon om mineral coal such as brown coal or other bituminous or carbonaceous matter by heating the same together with reducible substances, for example sulfates, at a suitable temperat-ure. Of importance for any process of transforming carbonaceous matter into decolorizing carbon is the thoroughgoing action upon the carbon substance treated since otherwise the surface increase f and roughening which is responsible for the decolorizing power cannot be obtained throughout the material. In order to secure this thorough-going effect it has further already been proposed (U. S. Patent .1,383,755 to Punnett and Whitaker), to

start from vegetable substances to impregnate the same, after due comminution with a suitable sulfate solution, to char the substance thus impregnated at a relatively low temperature and to thereupon subject it to eat treatment at a considerably increased temperature after separation of the reduction substance from the charred carbonizable material. It has further been proposed to impregnate already existing mineral coal or carbon with the reduction sulfate by a consecutive impregnation with sulfate component solutions, thus depositing the sulfate within the very pores or intersticesof the starting material (German Fat cut 248571 to Lotz) Finally 1t has already been proposed to mechanically mix the coal Application filed July 18, 1924. Seriar 1V0. 726,830.

to subject the mixture to'one heating oper-' ation at a relatively high temperature, whereupon the reduction substance is separated from the finished decolorizing carbon by a suitable cleansing operation and the carbon subjected, if necessary, to a short repeated heating (German Patent 310622 to Chemische Werke Carbon).

Contrary to'all of these known processes my present invention is substantiall based upon the discovery, that also alkal1-metalsulfur-compounds ada ted to be reduced to a sulfide by coal or carbon at a suitable temperature can also be used with particular advantage for the production of an excellent decolorizing carbon by mixing them in a dissolved or undissolved condition with the mineral coal or carbon and heating the mixture at a temperature of more than 600 C. As such alkali-metal sulfur-compounds the sulfates and bisulfates of the alkali metals or the component mixtures of these alkali compounds may with particular advantage be used.

As a matter of fact the whole pertinent literature which I know states a process of mixing an alkali metal sulfate with mineral coal or carbon and of heating the mixture out for a sufliciently long period of time and at a temperature of at least 600 C. Since alkali metal sulfate and alkali metal bisulfate may sometimes, particularly upon use of coarse or large-grained coal or carbon not enter deeply enough into and clog the pores, one has been dissuaded entirely from the use of the alkali-metal-sulfur-compounds in mechanical mixture with the carbonaceous starting material. My experiments and practical factory work have however shown that 'ust with the alkali-metal-sulfur-compoun an excellent decolorizing carbon can be obtained, particularly if the coal or carbon is comminuted before the heating oper -or carbon with an alkaline earth surfate and a ation into relatively small grains warranting the complete penetration with the sulfate or bisulfate to be reduced. If it is preferred ment may also eficiently be used with matter having before been comminuted into relatively small grains.

My process may be carried out with practically any mineral coal or carbon such as brown coal, bituminous coal, coke obtained by a distillation of coal or brown coal and the like. Regarding the proportions of the mixture the same can be so chosen that the reacting mixture obtained becomes liquid or remains in a solid condition, so that the process can be carried out with practically any type of furnace.

The use of the alkali metal sulfates or bisulfates or of their component mixtures as the substance to be reduced by the coal or carbon so as to change the texture thereof is of manifest practical advantage as these compounds are by the formation of the decolorizing carbon transferred into the valuable and soluble alkali metal sulfides, whereas upon the use of the alkaline earth sulfates the insoluble and valueless alkaline earth sulfides are produced which must be separated from the carbon by a cleansing operation, unlike the alkali metal sulfides which can be readily dissolved out with water. Regarding the proposal to mix mineral coal with an alkaline earth sulfate and to heat the same at a high temperature it would even be of advantage to use the alkaline earth bisulfates on account of their greater oxygen contents compared with the alkaline earth sulfate and of their accordingly more vigorous effect upon the carbon.

In carrying out my improved process 100 kg. of potassium sulfate were mixed with 80 kg. of charred brown coal and heated at 650- 700 C. during [;1 hour with the exclusion of oxygen or other oxidizing substance. After the heating the material was drawn into a rather tightly closing receptacle, cooled down and treated with water, thereby forming a solution of sulfide which could be subjected to further separate treatment, whereas the finished active coal was left and could be further purified according to its particular destination. In lieu=of 100-kg. of potassium sulfate one may also use 130 kg. of barium sulfate. One may also replace the potassium sulfate for example by an equivalent quantity of potassium chloride and sulfuric acid or an equivalent quantity of potassium bisulfate or of its constituting components.

What I claim as my invention is 1. The process of producing decolorizing carbon, comprising, mixing porous mineral coal with an alkali metal sulfur compound reducible to an alkali metal sulfide upon being heated with carbonaceous matter, heating the mixture at a temperature of at least 600 C. and subsequently dissolving out the alkali metal compounds from the carbon.

' 2. The process of producing decolorizing carbon, comprising, mechanically mixing porous mineral coal with an undissolved alkali metal sulfur compound reducible to an alkali metal sulfideupon being heated with carbonaceous matter, heating the mixture at a temperature of at least 600 (1., and dissolving out the alkali metal compounds from the carbon.

3. The process of producing decolorizing carbon, comprising, mixing porous mineral coal with an alkali metal sulfate, heating the mixture at a temperature of at least 600 (1, and dissolving out the alkali metal compounds from the carbon.

4:. The process of producing decolorizing carbon, comprising, mixing porous mineral coal with an alkali metal sulfur compound component mixture, heating the substances thus mixed at a temperature of at least 600 (3., and separating the carbon from the alkali metal compounds.

5. The process of producing decolorizing l carbon, comprising, mixing small' grained mineral coal with an alkali metal sulfate heating the mixture at a. temperature of at least 600 C., and dissolving out the alkali metal compounds from the carbon.

6. The process of producing decolorizing carbon, comprising, repeatedly mixing porous mineral coal with an alkali metal sulfate, heating the mixture at a temperature of at least 600 0., and dissolving out the alkali metal compounds from the carbon.

7. The process of producing decolorizing carbon, comprising, mixing small graine mineral coal with an alkali metal sulfate, heating the mixture at a temperature of at least 600 C., dissolving out the alkali metal compounds from the carbon, and repeating such steps up to the transformation of all of the mineral coal into decolorizing carbon.

8. The process of producing decolorizing carbon, comprising, mixing porous mineral coal with an alkali metal bisulfate, heating the mixture at a temperature of at least 600 (1, and dissolving out the alkali metal comter; heating the mixture under non-oxidizing conditions at a temperature of at least 600 (3., and subsequently dissolving out the alkali metal compound from the carbon.

'10. The process of producing decolorizin carbon comprising m1xing porous minera coal with'an alkah metal sulphur compound reducible to an alkali metal sulphide upon being heated with carbonaceous matter;

EliflL HENE. 

